Negative temperature coefficient of resistivity due to the itinerant spin fluctuations in metallic V$_{0.3}$Ti$_{0.7}$ alloy

Few concentrated disordered binary metallic alloys show a negative temperature coefficient of resistivity (TCR), which is quite unusual. V$_{0.3}$Ti$_{0.7}$ is one such alloy that shows resistivity exceeding 100 $\mu\Omega$ cm and exhibits negative TCR. The addition of ferromagnetic rare-earth Gd, which is insoluble in the body-centered cubic V-Ti matrix, changes the negative TCR to positive (when Gd conc. $\geq$ 2 at.$\%$). Evidence of spin polarization of conduction electrons of the V-Ti matrix by Gd clusters is obtained from the magnetization experiments as well as from the anomalous component of the Hall effect. Our analysis suggests that the additional scattering due to the distribution in the electron-spin fluctuation interaction arising from the substitution of titanium in vanadium is the origin of the negative TCR. The Gd clusters polarize the conduction electrons, leading to the suppression of spin fluctuations, resulting in the positive TCR.